1. Field of the Invention
The present invention relates generally to a probe cover for a probe component of an electronic thermometer.
Electronic thermometers have become useful and cost effective instruments in both human and veterinary medicine. Thermometers of this class usually include a probe member which is inserted into a cavity of a patient for taking a temperature measurement. A temperature sensing thermistor is normally provided at the sensing end of the probe, and is generally a permanent component of an electronic circuit in the thermometer. Disposable probe covers are often used with an electronic thermometer to bacteriologically isolate the probe from a patient while providing thermal contact with the body to enable the temperature to be sensed by the instrument. The use of a disposable probe cover readily facilitates the availability of a sanitary probe and cover for each new patient while eliminating the necessity for sterilization of the probe after each usage.
More particularly, the present invention pertains to an improved electronic thermometer probe cover which is designed to ensure that the cover is properly positioned on the probe before allowing a temperature measurement to be taken. Additionally, the cover provides for the discharge of any static charge which may accumulate thereon, an important consideration in some environments such as operating rooms.
2. Discussion of the Prior Art
Probe covers have generally been designed to conform to the shape of the probe with which they are to be utilized. For the most part, probe shafts are cylindrically shaped, and, accordingly, many probe covers have cylindrical configurations. The cylindrical configurations may include either straight walls, or tapered walls, or walls which taper to varying diameters through several sections.
For many applications it is desirable to have a probe cover formed of a rigid or semi-rigid material, normally a thermoplastic substance. A thermoplastic probe cover provides a sufficiently rigid structure to protect the mechanical components of the probe while maintaining sufficient flexibility to accommodate a patient's comfort.
Some thermoplastic probe covers in the prior art are provided with a metal tip at the sensing end thereof to provide improved thermal conductivity to the thermistor enclosed by the cover. Turner U.S. Pat. No. 4,117,926 utilizes an approach of this nature wherein a protective probe cover for an electronic thermometer has an elongated shaft or sleeve member formed of plastic which is provided with a metallic cap member at its sensing end.
Paull U.S. Pat. No. 4,007,832 illustrates a probe cover for an electronic thermometer which is formed of aluminum in a stepped diameter design. The aluminum cover is disclosed as providing a fast thermal response, while being comparatively economical to manufacture and utilize. Although this probe cover is electrically conductive, it is relatively rigid and is not formed of a flexible conductive plastic. Also it is not designed to be utilized with a verification circuit to ascertain that the disposable cover is properly positioned on the probe. Furthermore, the probe of Paull does not provide a grounding electrical contact for the probe, and accordingly even though the cover is conductive, the combination of the probe and cover would not provide for the discharge of static electrical charges from the aluminum cover.
Tong et al. U.S. Pat. No. 3,461,724 discloses a unique design for a probe cover for an electronic thermometer wherein the cover is a generally elongated hollow boot of a highly thermal conductive material such as aluminum foil. This probe cover is formed of aluminum foil because of its excellent heat conducting characteristics, and one skilled in this art would not be led by this patent to design a probe cover of a flexible conductive plastic. Furthermore, the aluminum foil probe is not designed to be utilized with a verification circuit to ascertain that the disposable cover is properly positioned on the probe. Although Tong et al. discloses an aluminum foil probe cover, the disclosed probe does not provide an electrical grounding contact for the cover, and accordingly the combination of the probe and cover would not provide for the discharge of static electricity from the foil cover.
Goldstein et al. U.S. Pat. No. 3,978,325 and Goldstein U.S. Pat. No. 4,068,526 disclose electronic thermometers of the type contemplated for usage with the teachings of the present invention. In greater particularity these patents disclose an electronic thermometer which provides an accurate final temperature reading prior to the actual stabilization of the temperature sensor. An algorithm is provided which allows taking only two sensor temperature measurements at preselected times to accurately predict the sensor final or stabilization temperature. Temperature resistance varying signals are converted to temperature-frequency varying signals, clocked into an up/down counter, to compute final temperature which is displayed digitally. A thirty-second timing sequence is also digitally displayed for use when the invention is utilized for medical applications.
Furthermore, Montren U.S. Pat. No. 4,166,389 discloses an electronic thermometer probe assembly which is suitable as a starting point for a redesigned probe assembly as disclosed herein. More particularly, Montren discloses a probe assembly designed to provide an instrument which is highly accurate and convenient to use. The thermometer includes a probe section having a flexible plastic shaft with a thermistor mounted at its tip. A disposable probe sheath covers the thermistor and flexible shaft, and is replaced after each measurement to ensure that the instrument remains uncontaminated. The sheath is cylindrically shaped, and has an open end which extends onto a conically-shaped retainer for the sheath. The thermometer handle includes an axially displaceable section, movement of which dislodges the sheath from the retainer to enable it to be disposed of conveniently.